Fluid dispensers are well known for use within institutional environments that require the sanitary and hygienic dispensation of substances such as soaps and shampoos. One known type of fluid dispenser is wall-mountable, and utilizes an internal bag or tube that is filled with fluid, such as liquid soap. The bag is flexible and disposable. Further, the bag has two chambers, namely, a main upper reservoir compartment and a lower dispensing bulb that is capable of holding a measured amount of fluid. A dispensing spout extends downwardly from the bulb, and hangs externally from the dispenser.
Various fluid dispensers have been proposed for use with such bags, utilizing both gravitational and mechanical forces. Such dispensers, however, typically have two major problems, namely the ability to effectively seal the opening between the main reservoir and the dispensing bulb, and the requirement of a relatively complex mechanical device to expel the fluid from the bag.
An attempt has been made to remedy these problems. U.S. Pat. No. 4,463,876 relates to a fluid dispensing device in which upper and lower pinching mechanisms are provided for pinching the discharge portion of the bag, below the main reservoir. The upper pinching mechanism includes a fixed jaw and a movable jaw, while the lower pinching mechanism includes two jaws which are each movable with respect to the stationary housing and with respect to one another. As a result, it is necessary to provide stops on the stationary housing which serves to limit the movement of one of the lower jaws while permitting continued movement of the other jaw. This arrangement therefore requires a complex mechanism which does not ensure a tight or effective seal between the movable lower jaws.